The Cold Chain

Authors: Dr. Jean-Paul Rodrigue and Matthew Craig

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1. Overview

While Globalization has made the relative distance between regions of the world much smaller, the physical separation of these same regions is still a very important reality. The greater the physical separation, the more likely freight can be damaged in one of the complex transport operations involved. It takes time and coordination to efficiently move a shipment and every delay can have negative consequences, particularly if this cargo is perishable. To ensure that cargo does not become damaged or compromised throughout this process, businesses in the pharmaceutical, medical and food industries are increasingly relying on the cold chain technology.

The cold chain refers to the transportation of temperature sensitive products along a supply chain through thermal and refrigerated packaging methods and the logistical planning to protect the integrity of these shipments.

Specialization has led many companies to not only rely on major shipping service providers such as the United Parcel Service (UPS) and FEDEX, but also more focused industry specialists that have developed a niche logistical expertise around the shipping of temperature sensitive products. The potential to understand local rules, customs and environmental conditions as well as an estimation of the length and time of a distribution route make them an important factor in global trade. As a result, the logistics industry is experiencing a growing level of specialization and segmentation of cold chain shipping in several potential niche markets within global commodity chains. Whole new segments of the distribution industry have been very active in taking advantage of the dual development of the spatial extension of supply chains supported by globalization and the significant variety of goods in circulation. From an economic development perspective, the cold chain enables many developing countries to take part in the global perishable products market. From a geographical perspective, the cold chain has the following impacts:

• Global. Specialization of agricultural functions permitting the transport of temperature sensitive food products to distant markets. Enables the distribution of vaccines and other pharmaceutical or biological products.
• Regional. Can support the specialization of functions and economies of scale, such as specialized laboratories.
• Local. Timely distribution to the final consumer, namely grocery stores and restaurants.

2. Emergence of Cold Chain Logistics

While global commodity chains are fairly modern expansions in the transportation industry, the refrigerated movement of temperature sensitive goods is a practice that dates back to 1797 when British fishermen used natural ice to preserve their fish stock piles. This process was also seen in the late 1800s for the movement of food from rural areas to urban consumption markets, namely dairy products. Cold storage was also a key component of food trade between colonial powers and their colonies. For example, in the late 1870s and early 1880s, France was starting to receive large shipments of frozen meat and mutton carcasses from South America, while Great Britain imported frozen beef from Australia and pork and other meat from New Zealand. By 1910, 600,000 tons of frozen meat was being brought into Great Britain alone.

The temperature controlled movement of pharmaceuticals and medical supplies is a much more modern transit option than the shipping of refrigerated or frozen food. Since the 1950s, logistical third party companies began to emerge and institute new methods for successfully transporting these global commodities. Before their emergence, cold chain processes were mostly managed in house by the manufacturer. In the United States, Food and Drug Administration restrictions and accountability measures over the stability of the cold chain incited many of these companies to rely on specialty couriers rather than completely overhauling their supply chain facilities. A specialized industry was thus born. The value of the cold chain in the preservation of expensive vaccines and medical supplies was only beginning to be recognized when these logistical providers started to appear. As awareness began to grow, so did the need for efficient management of the cold chain.

The reliance on the cold chain continues to gain importance. Within the pharmaceutical industry for instance, the testing, production and movement of drugs relies heavily on controlled and uncompromised transfer of shipments. A large portion of the pharmaceutical products that move along the cold chain are in the experiment or developmental phase. Clinical research and trials is a major part of the industry that costs millions of dollars, but one that also experiences a failure rate of around 80%. According to the Healthcare Distribution Management Association, of the close to 200 billion dollars in pharmaceutical distribution, about 10% are drugs that are temperature sensitive. This makes the cold chain responsible for transporting a near 20 billion dollar investment. If these shipments should experience any unanticipated exposure to variant temperature levels, they run the risk of becoming ineffective or even harmful to patients.

Temperature control in the shipment of foodstuffs is a component of the industry that has continued to rise in necessity with international trade. As more and more countries focus their primary or large portions of their export economy around food and produce production, the need to keep these products fresh for extended periods of time has gained in importance. Any major grocery store around the world is likely to carry tangerines from South Africa, apples from New Zealand, bananas from Costa Rica and asparagus from Mexico. Thus, a cold chain industry has emerged to service these commodity chains. In 2002, an estimated 1200 billion dollars worth of food was transported by a fleet of 400,000 refrigerated containers (Reefers). Alone, the United States imports about 30% of its fruits and vegetables and 20% of its food exports can be considered perishables. The uncompromised quality and safety of this food is often taken for granted, despite being the main reason behind the ability to sell the food. The cold chain serves the function of keeping food fresh for extended periods and eliminating doubts over the quality of the food products.

3. Food Transportation

There is a variety of methods for the transport of food products. Land, sea and air modes all have different structures for keeping food fresh throughout the transport chain. Innovations in packaging, fruit and vegetable coatings, bioengineering (controlled ripening), and other techniques reducing the deterioration of food products have helped shippers extend the reach of perishable products. Concomitantly, new transport technologies have permitted the shipment of perishable products over longer distances. For instance, improved roads and intermodal connections along the African coast reduced transport time for food to European markets from 10 days to 4 days.

Certain domestic or transnational supply chains may only require one transportation mode, but many times ground shipments are one link in a combination of transport modes. This makes intermodal transfer critical for the cold chain. Intermodal shipments typically use either 20 or 40 footers refrigerated containers that are capable of holding up to 26 tons of food. The container makes loading and unloading periods shorter and less susceptible to experiencing damage. The environments in these containers are currently controlled electronically by either plugging into a generator or power source on the ship or truck, but early food shipments would cycle air from stores of wet or dry ice to keep the food refrigerated.

Moving away from ice refrigeration has allowed for much greater distances to be traveled and has greatly increased the size of the global food market, enabling many developing countries to capture new opportunities. Another efficient mode for transporting foodstuffs is air travel. While this is a preferred form of travel for highly perishable and valuable goods due to its ability to move much faster over longer distances, it does lack the environment control and transfer ease of the ground and sea transports. Also, during the flight the cargo is stored in a 15°C – 20°C environment, but close to 80% of the time the package is exposed to exterior weather while waiting to be loaded onto the plane or being moved to and from the airfield. This is troubling considering the value of the food and the importance placed behind quality and freshness. In order for this form of food transport to experience growth among market users, more uncompromising strategies and regulations will have to be embraced and enacted.

Food transportation is an industry that has fully adapted to the cold chain and can, despite the problems with air transport, be considered the most resilient, particularly since a large majority of food products have a better tolerance to temporary variations of transport temperatures. As a result, small errors can be compounded without the concern of irreversible damage. For instance, for the transportation of produces, for every hour of delay in the pre-cooling of shipments, an equivalent one day loss of shelf life must be accounted. The usage of refrigerated containers has particularly helped, since they account for more than 50% of all the refrigerated cargo transported in the world. The efficiency and reliability of temperature controlled transportation has reached a point which allows the food industry to take advantage of global seasonable variations, meaning that during the winter the southern hemisphere can export perishable goods to the northern hemisphere while an opposite trade, generally of smaller scale, takes place during the summer. Countries such as Chile have substantially benefited from this and have developed an active agricultural and food transformation industry mainly servicing the North American market during the winter, but also with several niche markets such as wine.

4. Providing Temperature Controlled Environments

The success of industries that rely on the cold chain comes down to knowing how to ship a product with temperature control adapted to the shipping circumstances. Different products require different temperature level maintenance to ensure their integrity throughout the travel process. For instance, the most common temperature standards are  "banana" (13 °C), "chill" (2 °C), "frozen"  (-18 °C) and "deep frozen" (-29 °C). Staying within this temperature is vital to the integrity of a shipment along the supply chain. Any excursions can result in irrevocable and expensive damage; a product can simply lose any market or useful value. Being able to ensure that a shipment will remain within a temperature range for an extended period of time comes down largely to the type of container that is used and the refrigeration method. Factors such as duration of transit, the size of the shipment and the ambient or outside temperatures experienced are important in deciding what type of packaging is required. They can range from small insulated boxes that require dry ice or gel packs, rolling containers, to a 53 footer reefer that their own powered refrigeration units. The major cold chain technologies involve:

• Dry ice. Solid carbon dioxide, is about -80°C and is capable of keeping a shipment frozen for an extended period of time. It is particularly used for the shipping of pharmaceuticals, dangerous goods and foodstuffs. Dry ice does not melt, instead it sublimates when it comes in contact with the air.
• Gel packs. Large shares of pharmaceutical and medicinal shipments are classified as chilled products, which means they must be stored in a temperature range between 2 and 8°C. The common method to provide this temperature is to use gel packs, or packages that contain phase changing substances that can go from solid to liquid and vice versa to control an environment. Depending on the shipping requirements, these packs can either start off in a frozen or refrigerated state. Along the transit process they melt to liquids, while at the same time capturing escaping energy and maintaining an internal temperature.
• Eutectic plates. The principle is similar to gel packs. Instead, plates are filled with a liquid and can be reused many times.
• Liquid nitrogen. An especially cold substance, of about -196°C, used to keep packages frozen over a long period of time. Mainly used to transport biological cargo such as tissues and organs. Considered as an hazardous substance for the purpose of transportation.
• Quilts. Insulated pieces that are placed over or around freight to act as buffer in temperature variations and to maintain the temperature relatively constant. Thus, frozen freight will remain frozen for a longer time period, often long enough not to justify the usage of more expensive refrigeration devices. Quilts can also be used to keep temperature sensitive freight at room temperature while outside conditions can substantially vary (e.g. during the summer or the winter).
• Reefers. Generic name for a temperature controlled container, which can be a van, small truck, a semi or a standard ISO container. These containers, which are insulated, are specially designed to allow temperature controlled air circulation maintained by an attached and independent refrigeration plant.

5. The Setting and Organization of Cold Chains

Moving a shipment across the supply chain without suffering any setbacks or temperature anomalies requires the establishment of a comprehensive logistical process. This process concerns several phases ranging from the preparation of the shipments to final verification of the integrity of the shipment at the delivery point.

• Shipment preparation. When a temperature sensitive product is being moved, it is vital to first assess its characteristics. A key issue concerns the temperature conditioning of the shipment, which should be already at the desired temperature. Cold chain devices are commonly designed to keep a temperature constant, but not to bring a shipment to this temperature, so they would be unable to perform adequately if a shipment is not prepared. Other concerns include the destination of the shipment and the weather conditions for those regions, such as if the shipment will be exposed to extreme cold or heat along the transport route.
• Modal choice. Several key factors play into how the shipment will be moved. Distance between the origin and the final destination (which often includes a set of intermediary locations), the size and weight of the shipment, the required exterior temperature environment and any time restrictions of the product all effect the available transportation options. Short distances can be handled with a van or truck, while a longer trip may require an airplane or a container ship.
• Custom procedures. If the freight crosses boundaries, custom procedures can become very important, since cold chain products tend to be time sensitive and more subject to inspection than regular freight (e.g. pharmaceuticals and biological samples). The difficulty of this task differs depending on the nation (or economic bloc) and the gateway since there are variations in procedures and delays.
• The "Last Mile". The last stage is the actual delivery of the shipment to its destination, which in logistics is often known as the “last mile”. Key considerations when arranging a final delivery concern not only the destination, but the timing. Trucks and vans, the primary modes of transportation for this stage, must meet the specifications necessary to transfer the cold chain shipment. Also important is the final transfer of the shipment into the storage facilities as there is potential for a breach of integrity.
• Integrity and quality assurance. After the shipment has been delivered, any temperature recording devices or known temperature anomalies must be recorded and made known. This is the step of the logistical process that creates trust and accountability, particularly if liability for a damaged shipment is incurred. If problems or anomalies that compromise a shipment do occur, an effort must be made to identify the source and find corrective actions.